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Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs fixes from Al Viro: "Switch mnt_hash to hlist, turning the races between __lookup_mnt() and hash modifications into false negatives from __lookup_mnt() (instead of hangs)" On the false negatives from __lookup_mnt(): "The *only* thing we care about is not getting stuck in __lookup_mnt(). If it misses an entry because something in front of it just got moved around, etc, we are fine. We'll notice that mount_lock mismatch and that'll be it" * 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: switch mnt_hash to hlist don't bother with propagate_mnt() unless the target is shared keep shadowed vfsmounts together resizable namespace.c hashes
This commit is contained in:
Linus Torvalds
commit
fedc1ed0f1
@ -19,13 +19,13 @@ struct mnt_pcp {
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};
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struct mountpoint {
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struct list_head m_hash;
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struct hlist_node m_hash;
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struct dentry *m_dentry;
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int m_count;
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};
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struct mount {
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struct list_head mnt_hash;
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struct hlist_node mnt_hash;
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struct mount *mnt_parent;
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struct dentry *mnt_mountpoint;
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struct vfsmount mnt;
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177
fs/namespace.c
177
fs/namespace.c
@ -23,11 +23,34 @@
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#include <linux/uaccess.h>
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#include <linux/proc_ns.h>
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#include <linux/magic.h>
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#include <linux/bootmem.h>
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#include "pnode.h"
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#include "internal.h"
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#define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head))
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#define HASH_SIZE (1UL << HASH_SHIFT)
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static unsigned int m_hash_mask __read_mostly;
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static unsigned int m_hash_shift __read_mostly;
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static unsigned int mp_hash_mask __read_mostly;
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static unsigned int mp_hash_shift __read_mostly;
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static __initdata unsigned long mhash_entries;
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static int __init set_mhash_entries(char *str)
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{
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if (!str)
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return 0;
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mhash_entries = simple_strtoul(str, &str, 0);
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return 1;
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}
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__setup("mhash_entries=", set_mhash_entries);
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static __initdata unsigned long mphash_entries;
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static int __init set_mphash_entries(char *str)
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{
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if (!str)
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return 0;
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mphash_entries = simple_strtoul(str, &str, 0);
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return 1;
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}
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__setup("mphash_entries=", set_mphash_entries);
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static int event;
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static DEFINE_IDA(mnt_id_ida);
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@ -36,8 +59,8 @@ static DEFINE_SPINLOCK(mnt_id_lock);
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static int mnt_id_start = 0;
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static int mnt_group_start = 1;
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static struct list_head *mount_hashtable __read_mostly;
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static struct list_head *mountpoint_hashtable __read_mostly;
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static struct hlist_head *mount_hashtable __read_mostly;
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static struct hlist_head *mountpoint_hashtable __read_mostly;
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static struct kmem_cache *mnt_cache __read_mostly;
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static DECLARE_RWSEM(namespace_sem);
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@ -55,12 +78,19 @@ EXPORT_SYMBOL_GPL(fs_kobj);
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*/
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__cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock);
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static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
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static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry)
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{
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unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
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tmp += ((unsigned long)dentry / L1_CACHE_BYTES);
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tmp = tmp + (tmp >> HASH_SHIFT);
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return tmp & (HASH_SIZE - 1);
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tmp = tmp + (tmp >> m_hash_shift);
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return &mount_hashtable[tmp & m_hash_mask];
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}
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static inline struct hlist_head *mp_hash(struct dentry *dentry)
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{
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unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES);
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tmp = tmp + (tmp >> mp_hash_shift);
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return &mountpoint_hashtable[tmp & mp_hash_mask];
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}
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/*
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@ -187,7 +217,7 @@ static struct mount *alloc_vfsmnt(const char *name)
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mnt->mnt_writers = 0;
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#endif
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INIT_LIST_HEAD(&mnt->mnt_hash);
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INIT_HLIST_NODE(&mnt->mnt_hash);
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INIT_LIST_HEAD(&mnt->mnt_child);
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INIT_LIST_HEAD(&mnt->mnt_mounts);
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INIT_LIST_HEAD(&mnt->mnt_list);
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@ -575,10 +605,10 @@ bool legitimize_mnt(struct vfsmount *bastard, unsigned seq)
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*/
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struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
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{
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struct list_head *head = mount_hashtable + hash(mnt, dentry);
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struct hlist_head *head = m_hash(mnt, dentry);
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struct mount *p;
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list_for_each_entry_rcu(p, head, mnt_hash)
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hlist_for_each_entry_rcu(p, head, mnt_hash)
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if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry)
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return p;
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return NULL;
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@ -590,13 +620,17 @@ struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
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*/
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struct mount *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry)
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{
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struct list_head *head = mount_hashtable + hash(mnt, dentry);
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struct mount *p;
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list_for_each_entry_reverse(p, head, mnt_hash)
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if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry)
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return p;
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return NULL;
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struct mount *p, *res;
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res = p = __lookup_mnt(mnt, dentry);
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if (!p)
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goto out;
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hlist_for_each_entry_continue(p, mnt_hash) {
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if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry)
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break;
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res = p;
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}
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out:
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return res;
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}
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/*
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@ -633,11 +667,11 @@ struct vfsmount *lookup_mnt(struct path *path)
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static struct mountpoint *new_mountpoint(struct dentry *dentry)
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{
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struct list_head *chain = mountpoint_hashtable + hash(NULL, dentry);
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struct hlist_head *chain = mp_hash(dentry);
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struct mountpoint *mp;
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int ret;
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list_for_each_entry(mp, chain, m_hash) {
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hlist_for_each_entry(mp, chain, m_hash) {
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if (mp->m_dentry == dentry) {
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/* might be worth a WARN_ON() */
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if (d_unlinked(dentry))
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@ -659,7 +693,7 @@ static struct mountpoint *new_mountpoint(struct dentry *dentry)
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mp->m_dentry = dentry;
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mp->m_count = 1;
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list_add(&mp->m_hash, chain);
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hlist_add_head(&mp->m_hash, chain);
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return mp;
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}
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@ -670,7 +704,7 @@ static void put_mountpoint(struct mountpoint *mp)
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spin_lock(&dentry->d_lock);
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dentry->d_flags &= ~DCACHE_MOUNTED;
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spin_unlock(&dentry->d_lock);
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list_del(&mp->m_hash);
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hlist_del(&mp->m_hash);
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kfree(mp);
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}
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}
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@ -712,7 +746,7 @@ static void detach_mnt(struct mount *mnt, struct path *old_path)
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mnt->mnt_parent = mnt;
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mnt->mnt_mountpoint = mnt->mnt.mnt_root;
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list_del_init(&mnt->mnt_child);
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list_del_init(&mnt->mnt_hash);
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hlist_del_init_rcu(&mnt->mnt_hash);
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put_mountpoint(mnt->mnt_mp);
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mnt->mnt_mp = NULL;
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}
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@ -739,15 +773,14 @@ static void attach_mnt(struct mount *mnt,
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struct mountpoint *mp)
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{
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mnt_set_mountpoint(parent, mp, mnt);
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list_add_tail(&mnt->mnt_hash, mount_hashtable +
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hash(&parent->mnt, mp->m_dentry));
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hlist_add_head_rcu(&mnt->mnt_hash, m_hash(&parent->mnt, mp->m_dentry));
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list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
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}
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/*
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* vfsmount lock must be held for write
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*/
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static void commit_tree(struct mount *mnt)
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static void commit_tree(struct mount *mnt, struct mount *shadows)
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{
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struct mount *parent = mnt->mnt_parent;
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struct mount *m;
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@ -762,8 +795,11 @@ static void commit_tree(struct mount *mnt)
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list_splice(&head, n->list.prev);
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list_add_tail(&mnt->mnt_hash, mount_hashtable +
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hash(&parent->mnt, mnt->mnt_mountpoint));
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if (shadows)
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hlist_add_after_rcu(&shadows->mnt_hash, &mnt->mnt_hash);
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else
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hlist_add_head_rcu(&mnt->mnt_hash,
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m_hash(&parent->mnt, mnt->mnt_mountpoint));
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list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
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touch_mnt_namespace(n);
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}
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@ -1153,26 +1189,28 @@ int may_umount(struct vfsmount *mnt)
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EXPORT_SYMBOL(may_umount);
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static LIST_HEAD(unmounted); /* protected by namespace_sem */
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static HLIST_HEAD(unmounted); /* protected by namespace_sem */
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static void namespace_unlock(void)
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{
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struct mount *mnt;
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LIST_HEAD(head);
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struct hlist_head head = unmounted;
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if (likely(list_empty(&unmounted))) {
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if (likely(hlist_empty(&head))) {
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up_write(&namespace_sem);
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return;
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}
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list_splice_init(&unmounted, &head);
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head.first->pprev = &head.first;
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INIT_HLIST_HEAD(&unmounted);
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up_write(&namespace_sem);
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synchronize_rcu();
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while (!list_empty(&head)) {
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mnt = list_first_entry(&head, struct mount, mnt_hash);
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list_del_init(&mnt->mnt_hash);
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while (!hlist_empty(&head)) {
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mnt = hlist_entry(head.first, struct mount, mnt_hash);
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hlist_del_init(&mnt->mnt_hash);
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if (mnt->mnt_ex_mountpoint.mnt)
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path_put(&mnt->mnt_ex_mountpoint);
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mntput(&mnt->mnt);
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@ -1193,16 +1231,19 @@ static inline void namespace_lock(void)
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*/
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void umount_tree(struct mount *mnt, int how)
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{
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LIST_HEAD(tmp_list);
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HLIST_HEAD(tmp_list);
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struct mount *p;
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struct mount *last = NULL;
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for (p = mnt; p; p = next_mnt(p, mnt))
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list_move(&p->mnt_hash, &tmp_list);
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for (p = mnt; p; p = next_mnt(p, mnt)) {
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hlist_del_init_rcu(&p->mnt_hash);
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hlist_add_head(&p->mnt_hash, &tmp_list);
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}
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if (how)
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propagate_umount(&tmp_list);
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list_for_each_entry(p, &tmp_list, mnt_hash) {
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hlist_for_each_entry(p, &tmp_list, mnt_hash) {
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list_del_init(&p->mnt_expire);
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list_del_init(&p->mnt_list);
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__touch_mnt_namespace(p->mnt_ns);
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@ -1220,8 +1261,13 @@ void umount_tree(struct mount *mnt, int how)
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p->mnt_mp = NULL;
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}
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change_mnt_propagation(p, MS_PRIVATE);
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last = p;
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}
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if (last) {
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last->mnt_hash.next = unmounted.first;
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unmounted.first = tmp_list.first;
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unmounted.first->pprev = &unmounted.first;
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}
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list_splice(&tmp_list, &unmounted);
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}
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static void shrink_submounts(struct mount *mnt);
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@ -1605,24 +1651,23 @@ static int attach_recursive_mnt(struct mount *source_mnt,
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struct mountpoint *dest_mp,
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struct path *parent_path)
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{
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LIST_HEAD(tree_list);
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HLIST_HEAD(tree_list);
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struct mount *child, *p;
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struct hlist_node *n;
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int err;
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|
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if (IS_MNT_SHARED(dest_mnt)) {
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err = invent_group_ids(source_mnt, true);
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if (err)
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goto out;
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}
|
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err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list);
|
||||
if (err)
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||||
goto out_cleanup_ids;
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||||
|
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lock_mount_hash();
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|
||||
if (IS_MNT_SHARED(dest_mnt)) {
|
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err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list);
|
||||
if (err)
|
||||
goto out_cleanup_ids;
|
||||
lock_mount_hash();
|
||||
for (p = source_mnt; p; p = next_mnt(p, source_mnt))
|
||||
set_mnt_shared(p);
|
||||
} else {
|
||||
lock_mount_hash();
|
||||
}
|
||||
if (parent_path) {
|
||||
detach_mnt(source_mnt, parent_path);
|
||||
@ -1630,20 +1675,22 @@ static int attach_recursive_mnt(struct mount *source_mnt,
|
||||
touch_mnt_namespace(source_mnt->mnt_ns);
|
||||
} else {
|
||||
mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt);
|
||||
commit_tree(source_mnt);
|
||||
commit_tree(source_mnt, NULL);
|
||||
}
|
||||
|
||||
list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
|
||||
list_del_init(&child->mnt_hash);
|
||||
commit_tree(child);
|
||||
hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) {
|
||||
struct mount *q;
|
||||
hlist_del_init(&child->mnt_hash);
|
||||
q = __lookup_mnt_last(&child->mnt_parent->mnt,
|
||||
child->mnt_mountpoint);
|
||||
commit_tree(child, q);
|
||||
}
|
||||
unlock_mount_hash();
|
||||
|
||||
return 0;
|
||||
|
||||
out_cleanup_ids:
|
||||
if (IS_MNT_SHARED(dest_mnt))
|
||||
cleanup_group_ids(source_mnt, NULL);
|
||||
cleanup_group_ids(source_mnt, NULL);
|
||||
out:
|
||||
return err;
|
||||
}
|
||||
@ -2777,18 +2824,24 @@ void __init mnt_init(void)
|
||||
mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount),
|
||||
0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
|
||||
|
||||
mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
|
||||
mountpoint_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
|
||||
mount_hashtable = alloc_large_system_hash("Mount-cache",
|
||||
sizeof(struct hlist_head),
|
||||
mhash_entries, 19,
|
||||
0,
|
||||
&m_hash_shift, &m_hash_mask, 0, 0);
|
||||
mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache",
|
||||
sizeof(struct hlist_head),
|
||||
mphash_entries, 19,
|
||||
0,
|
||||
&mp_hash_shift, &mp_hash_mask, 0, 0);
|
||||
|
||||
if (!mount_hashtable || !mountpoint_hashtable)
|
||||
panic("Failed to allocate mount hash table\n");
|
||||
|
||||
printk(KERN_INFO "Mount-cache hash table entries: %lu\n", HASH_SIZE);
|
||||
|
||||
for (u = 0; u < HASH_SIZE; u++)
|
||||
INIT_LIST_HEAD(&mount_hashtable[u]);
|
||||
for (u = 0; u < HASH_SIZE; u++)
|
||||
INIT_LIST_HEAD(&mountpoint_hashtable[u]);
|
||||
for (u = 0; u <= m_hash_mask; u++)
|
||||
INIT_HLIST_HEAD(&mount_hashtable[u]);
|
||||
for (u = 0; u <= mp_hash_mask; u++)
|
||||
INIT_HLIST_HEAD(&mountpoint_hashtable[u]);
|
||||
|
||||
kernfs_init();
|
||||
|
||||
|
||||
26
fs/pnode.c
26
fs/pnode.c
@ -220,14 +220,14 @@ static struct mount *get_source(struct mount *dest,
|
||||
* @tree_list : list of heads of trees to be attached.
|
||||
*/
|
||||
int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp,
|
||||
struct mount *source_mnt, struct list_head *tree_list)
|
||||
struct mount *source_mnt, struct hlist_head *tree_list)
|
||||
{
|
||||
struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
|
||||
struct mount *m, *child;
|
||||
int ret = 0;
|
||||
struct mount *prev_dest_mnt = dest_mnt;
|
||||
struct mount *prev_src_mnt = source_mnt;
|
||||
LIST_HEAD(tmp_list);
|
||||
HLIST_HEAD(tmp_list);
|
||||
|
||||
for (m = propagation_next(dest_mnt, dest_mnt); m;
|
||||
m = propagation_next(m, dest_mnt)) {
|
||||
@ -246,27 +246,29 @@ int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp,
|
||||
child = copy_tree(source, source->mnt.mnt_root, type);
|
||||
if (IS_ERR(child)) {
|
||||
ret = PTR_ERR(child);
|
||||
list_splice(tree_list, tmp_list.prev);
|
||||
tmp_list = *tree_list;
|
||||
tmp_list.first->pprev = &tmp_list.first;
|
||||
INIT_HLIST_HEAD(tree_list);
|
||||
goto out;
|
||||
}
|
||||
|
||||
if (is_subdir(dest_mp->m_dentry, m->mnt.mnt_root)) {
|
||||
mnt_set_mountpoint(m, dest_mp, child);
|
||||
list_add_tail(&child->mnt_hash, tree_list);
|
||||
hlist_add_head(&child->mnt_hash, tree_list);
|
||||
} else {
|
||||
/*
|
||||
* This can happen if the parent mount was bind mounted
|
||||
* on some subdirectory of a shared/slave mount.
|
||||
*/
|
||||
list_add_tail(&child->mnt_hash, &tmp_list);
|
||||
hlist_add_head(&child->mnt_hash, &tmp_list);
|
||||
}
|
||||
prev_dest_mnt = m;
|
||||
prev_src_mnt = child;
|
||||
}
|
||||
out:
|
||||
lock_mount_hash();
|
||||
while (!list_empty(&tmp_list)) {
|
||||
child = list_first_entry(&tmp_list, struct mount, mnt_hash);
|
||||
while (!hlist_empty(&tmp_list)) {
|
||||
child = hlist_entry(tmp_list.first, struct mount, mnt_hash);
|
||||
umount_tree(child, 0);
|
||||
}
|
||||
unlock_mount_hash();
|
||||
@ -338,8 +340,10 @@ static void __propagate_umount(struct mount *mnt)
|
||||
* umount the child only if the child has no
|
||||
* other children
|
||||
*/
|
||||
if (child && list_empty(&child->mnt_mounts))
|
||||
list_move_tail(&child->mnt_hash, &mnt->mnt_hash);
|
||||
if (child && list_empty(&child->mnt_mounts)) {
|
||||
hlist_del_init_rcu(&child->mnt_hash);
|
||||
hlist_add_before_rcu(&child->mnt_hash, &mnt->mnt_hash);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
@ -350,11 +354,11 @@ static void __propagate_umount(struct mount *mnt)
|
||||
*
|
||||
* vfsmount lock must be held for write
|
||||
*/
|
||||
int propagate_umount(struct list_head *list)
|
||||
int propagate_umount(struct hlist_head *list)
|
||||
{
|
||||
struct mount *mnt;
|
||||
|
||||
list_for_each_entry(mnt, list, mnt_hash)
|
||||
hlist_for_each_entry(mnt, list, mnt_hash)
|
||||
__propagate_umount(mnt);
|
||||
return 0;
|
||||
}
|
||||
|
||||
@ -36,8 +36,8 @@ static inline void set_mnt_shared(struct mount *mnt)
|
||||
|
||||
void change_mnt_propagation(struct mount *, int);
|
||||
int propagate_mnt(struct mount *, struct mountpoint *, struct mount *,
|
||||
struct list_head *);
|
||||
int propagate_umount(struct list_head *);
|
||||
struct hlist_head *);
|
||||
int propagate_umount(struct hlist_head *);
|
||||
int propagate_mount_busy(struct mount *, int);
|
||||
void mnt_release_group_id(struct mount *);
|
||||
int get_dominating_id(struct mount *mnt, const struct path *root);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user